This invention relates generally to an apparatus for providing fluid to a rotable member and particularly to such an apparatus for providing a flammable gas to a rotating burner.
The production of many commercial items requires the sealing of glass parts. An example of such a part is a color picture tube (kinescope) for a color television receiver. A kinescope includes a neck portion in which electron guns are mounted. The electron guns provide the electron beams needed to generate a color image on the screen of the tube. One of the manufacturing steps of the kinescope is that of mounting and sealing the electron guns into the neck of the tube. Typically, the sealing is done using a rotatable gas burner to heat the glass neck of the kinescope bulb. The heated neck glass molds to a glass support member which supports the electron guns by control electrodes passing through the end of the tube neck. The gas burner is rotated about the neck to heat the neck glass and cause the glass to become malleable and weld to the glass support. The burner is rotated about the neck in order to uniformly heat the neck and the support glass to avoid cracking and deformation of the neck glass. The gas is highly flammable and therefore it is very important that the rotating assembly is leak proof to avoid potentially dangerous situations. Typically, the seals of the rotating assembly used to provide gas to the rotating burner have a very short life and the burner assembly must be taken out of service while the seals are replaced.
Long-lasting, non-mechanical ferrofluid seals are presently available in the art. However, such seals are not presently adaptable to providing flammable gas to a rotating burner. In ferrofluid seals a torroidal magnet is 35 arranged between two ferromagnetic end closures. A shaft is arranged to pass through the centers of the torroidal magnet and the end closures, and is mounted in bearings to rotate within the end closures and the magnet. The shaft is grooved in the areas where it passes through the bores of the end closures to provide small clearances between the shaft and the walls of the bores in the end closures. A ferrofluid is provided in the grooves of the shaft. A magnetic flux path is thereby established through the torroidal magnet, the end closures and the shaft. This magnetic field attracts the ferrofluid into the small clearances between the shaft and the bores of the end closures to form a very effective fluid seal. Because the sealing material is a fluid, it is not subject to wear and the seal has very long life. Such shields are presently available in the art. However, they are not presently adaptable to the provision of a flammable gas to a rotating burner. The present invention provides an adaptation for such use.